🌿 Magnesium Glycinate vs Citrate vs Oxide Bioavailability Simulator

Swallowing the Magnesium Salt

One tablet, three chemical forms, three very different fates.

• 14%: Elemental Mg — Glycinate (by tablet weight)
• 16%: Elemental Mg — Citrate (by tablet weight)
• 60%: Elemental Mg — Oxide (highest, but poorly absorbed)
• 310–420mg: RDA adult magnesium (per day)

Same mineral, different carrier

Magnesium is bound to a partner molecule. The partner decides how well it dissolves and absorbs.

Why form matters more than dose

A high-elemental oxide tablet can absorb worse than a small glycinate dose. Bioavailability beats raw milligrams.

Gut Dissolution Kinetics

Stomach acid and small intestine fluid break the salt apart.

• Fast: Glycinate dissolution (chelated, water-soluble)
• Fast-moderate: Citrate dissolution (organic acid salt)
• Slow: Oxide dissolution (low water solubility)
• High (oxide): pH dependence (needs strong acid)

Chelation speeds release

Glycinate binds magnesium to glycine, an amino acid. This chelate stays soluble through the gut.

Oxide resists dissolving

Oxide is an inorganic salt with low solubility. Much of it stays undissolved in the lumen.

Crossing the Intestinal Wall

Only dissolved, free Mg²⁺ ions can cross into the bloodstream.

• ~80%: Glycinate absorption (amino acid transporter route)
• ~35%: Citrate absorption (paracellular + carrier)
• ~4%: Oxide absorption (mostly stays in lumen)
• Small intestine: Absorption site (jejunum & ileum)

Two absorption routes

Active transport favors chelated glycinate. Passive paracellular flow favors citrate somewhat.

Unabsorbed magnesium pulls water

Undissolved oxide draws water osmotically into the gut. This produces its strong laxative pull.

Blood Magnesium Rise

Absorbed ions raise serum magnesium at different rates.

• +0.6 mg/dL: Glycinate blood rise (highest, steady)
• +0.4 mg/dL: Citrate blood rise (moderate)
• +0.1 mg/dL: Oxide blood rise (lowest)
• 1.7–2.2 mg/dL: Normal serum Mg (reference range)

Bioavailable does not mean dosed

Only the fraction that crosses the gut wall counts. Label milligrams overstate oxide's real delivery.

Steady vs blunted rise

Glycinate produces a smoother rise, less GI upset. Oxide's rise is small and often diarrhea-limited.

Matching Form to Health Goal

The best form depends on what you are trying to fix.

• Glycinate: Best for sleep (calming, low GI upset)
• Oxide: Best for digestion (osmotic, laxative effect)
• Citrate: Best for deficiency (good absorption, low cost)
• Oxide: Worst general choice (for raising blood Mg)

Sleep and calm goals

Glycinate crosses well and avoids gut irritation. Glycine itself has a mild calming effect.

Digestion and constipation goals

Oxide's poor absorption is the whole point here. Unabsorbed salt draws water, easing constipation.

General deficiency correction

Citrate balances decent absorption and affordability. It is a common first-line supplement choice.

Form comparison at a glance